It started out with my anti-virus (Avast!) not updating properly, then the anti-virus started crashing. I tried to re-install it, which didn't work. I then uninstalled Avast! and installed AVG, which worked for a while, and then started having the same issues. I tried to re-install AVG, and it kept falling over. Not only failing to update, but eventually crashing also.

Then Thunderbird started crashing. Re-install that, and it seems to have cured it.

Then Firefox starts to crash... and crash... and crash... and crash, much so that it wouldn't even start up before falling over. I tried reinstalling it - it would work, then crash again.

Un-install Firefox, then do what I thought was a clean install of version 3.0.11. This worked to a certain extent, but now the new install wouldn't let me type in URLs in the address bar. Or rather, it would let me type it in, but then it would sit there and refuse to do anything when I hit Enter. AARRRRGGGHHHH!!!

Finally posted on the Firefox support forum, which suggested completely uninstalling, and then manually deleting the left over program folder. Much to my relief, this worked to cure the address bar problem, and it's now working, but it's still crashing at intervals, completely at random, which makes it really annoying.

Plus I still have other programs crashing at random intervals, like Zone Alarm, and pretty much everything else, although the new anti-virus seems to be working properly so far (fingers crossed).

On the positive side, I did discover a couple of FF extensions I didn't know about before. One is called FEBE, and allows you to back up all the settings and extensions of Firefox to a separate directory. The other is called Lazarus, and it allows any text typed into a form to be retrieved in case of Firefox crashing. I wish I'd known about these two before I ended up having to manually rebuild my Firefox installation more or less from scratch...